A conventional process for producing a magnetic recording medium that is commonly employed in the art comprises coating a magnetic coating composition to a non-magnetic support, drying the coating, smoothing the coated layer by the use of a calendar composed of a mirror-finished metal roller and an elastic roller, and then crosslinking a binder by, for example, heating. However, this conventional process involves a smoothing step using several rollers at strictly controlled conditions with respect to temperature and pressure apart from coating and drying steps, and therefore entails high costs. Further, magnetic recording media have recently been demanded to have high electromagnetic properties and running durability, but these requirements are not fully satisfied by the conventional process.
In an attempt to eliminate the above-described problems, it has been described to use a radiation-polymerizable compound as a binder in place of a thermosetting compound, e.g., a polyisocyanate compound, which can be cured upon irradiation as described, e.g., in Japanese Patent Application (OPI) Nos. 25231/81, 122802/81 and 124119/81 (the term "OPI" used herein refers to an "unexamined published application"). However, the use of only a radiation-polymerizable compound as a binder failed to solve the above-described problems.
On the other hand, a technique of transfer coating has been described by Dr. Nablo in Symposium on Magnetic Media Manufacturing Methods (May, 1983, Honolulu) (Paper No. B-4), aiming at improvement of surface smoothness of a coated layer. This technique, however, could not succeed to increase a concentration of ferromagnetic fine powders, i.e., the so-called pigment/vehicle ratio, and is, therefore, not practicable for the production of magnetic recording media. In other words, the process described by Dr. Nablo is not capable of ensuring sufficient electromagnetic properties and cannot be industrially employed as a process for producing a magnetic recording medium.